SYNTHESIS, DEPROTONATION, AND RING EXPANS ION OF A 2,3-DIBORATETRALIN

Reaction of K2[1,2-C6H4(CH2)2] with [Cl(Me2N)B]2 leads to 2,3-bis(dime thylamino)-2,3-diboratetralin (4a) in 58% yield. Deprotonation of 4a w ith lithium 2,2,6,6-tetramethylpiperidide yields the crystalline dilit hium salt 6a. Insertion of 3-hexyne into the B-B bond of 4a results in the formation of 2,5-bis(dimethylamino)-3,4 -diethyl-1,2,5,6-tetrahyd ro-2,5-benzodiborocine (7a) in 38% yield. The constitutions of 4a, 6a, and 7a were derived from H-1-, B-11-, C-13-NMR, and MS data and prove n for 6a and 7a by X-ray structure analyses.